Industrial robots for use in connection with various welding processes, such as spot welding, are now quite well known and have been in use for several decades. They are especially useful in production lines, such as for the production of cars, and then primarily for welding together car body parts or the like. In such applications, the robots must have a minimum size and rigidity so that they can apply the weld spot to the appropriate location, but at the same time they must be sufficiently flexible so that they can reach difficult locations. The spot weld itself is obtained by means of a current pulse of alternating or direct current having a high amperage, usually on the order of about 5,000 to 30,000 amperes. Therefore, it is necessary that thick cables be drawn to the welding jaw from a transformer, which is usually arranged in the vicinity of the base of the robot arm. However, these thick current cables, which hang outside the robot arm in some manner, presents a large hindrance to the movements of the robot arm. The robot arm must be able to swing in different directions, and even turn around an axis, so that the cable must therefore be relatively long, so that it can follow all of these movements of the arm. Besides the supply of current through such a thick current cable, it is also necessary to supply cooling water and pressure air for the various operations of the welding jaw. This, in turn, requires additional pipes and/or flexible hoses.
Similar such problems arise even in the cases where weaker currents need to be supplied to means other than a welding jaw. For example, these can be electrically controlled valves, gripping means or other such tools and the like.
Other such arrangements than these mentioned above, which do not require an electrical current, but which only need to be cooled or supplied with a liquid or gaseous medium, also are faced with the problems mentioned above, for example, those relating to space for flexible hoses and the like, which limits the movability of a robot arm.
Although the above-mentioned robots have been highly developed, and have functioned well for many years, they nevertheless have the serious limitation that, due to the thick cables and hoses required, the robot arm cannot reach all of the necessary locations. This renders production more difficult, and the construction of the articles which are to be welded, such as auto bodies, must therefore be adapted to the limitations of the robot. Since the initial use of such robots for spot welding and the like, it has been desired that one should be able to render the robot arm, with an additional welding jaw or the like, more flexible, so that all of the potential welding points or the like can be reached.